Quantitative assessment of motor neglect

Abstract

<jats:p>Objectives. Patients with unilateral brain damage may avoid moving the limbs contralateral to their lesion, even in the absence of sensorimotor deficits. However, when asked to move their limbs these patients typically show normal strength and dexterity. In their seminal 1983 article on the Journal of Neurology, Neurosurgery and Psychiatry, Laplane and Degos dubbed this condition Motor Neglect (MN). MN can mimic hemiplegia, with severe clinical consequences. Its assessment has thus important clinical implications. However, MN diagnosis is at present highly subjective, because it is based on the clinical observation of patients' spontaneous motor behaviour. Here we introduce differential actigraphy as a novel, objective method to quantify MN. Methods. Patients wear wristwatch-like accelerometers, which record spontaneous motor activity of their upper limbs during 24 hours. Asymmetries of motor behaviour are then automatically computed offline. On the basis of normal participants' performance, we calculated cut-off scores of left/right motor asymmetry. Results. Differential actigraphy showed contralesional MN in nine of 35 patients with unilateral strokes, consistent with clinical assessment. An additional patient with clinical signs of MN obtained a borderline asymmetry score. Lesion location in a subgroup of 25 patients was highly variable, suggesting that MN is a heterogenous condition. Conclusions. Differential actigraphy provides an ecological measure of spontaneous motor behaviour, and can assess upper limb motricity in an objective and quantitative manner. It thus offers a convenient, cost-effective, and relatively automatized procedure for following-up motor behaviour in neurological patients, and to assess the effects of rehabilitation.</jats:p>